svg_view: fix pattern matrix in create_surface_pattern.
svg_view: fix pattern matrix in create_surface_pattern.

There was a mismatch in x_scale and y_scale computation.
And the matrix == NULL case was wrong.

wavewave/lasem,wavewave/lasem,janmarthedal/mathml2svg,janmarthedal/mathml2svg,gjtorikian/lasem,gjtorikian/lasem,gjtorikian/lasem,janmarthedal/mathml2svg,wavewave/lasem,janmarthedal/mathml2svg,gjtorikian/lasem,wavewave/lasem